1. Field of the Invention
This invention relates to improved fireplaces in which means are provided for supplying combustion air to the fireplace from a point remote from the room in which the fireplace is located so that heated air will not be withdrawn from a home during operation of the fireplace.
2. Description of the Prior Art
It has long been recognized that a fireplace is not a particularly efficient means for producing heat for a home or other building. Conventional fireplaces may actually place an added burden on the central heating system of a home because the air to support combustion is drawn from the room into the fireplace and vented up the chimney. The air withdrawn from the room necessarily must be replaced by outside air which seeps into the home variously through windows, doors, electric outlets and the like, and this flow of air will cause a draft through the house that will cool those portions of the house that are not immediately adjacent the radiant glow of the fire. This draft may also be felt on the floor even in the immediate vicinity of the fireplace. Some studies have even indicated that fireplaces may withdraw as much or more heat than they supply, and so, realistically, it must be said that fireplaces have little practical value other than their nostalgia and aesthetic charm.
In older types of construction, before energy costs soared to such extravagant levels, houses were not always well insulated and the air withdrawn from the house by a fireplace was not noticeable in view of the otherwise naturally drafty condition of the house. However, now that greater concern is being shown for the conservation of energy and the reduction of heating bills, houses are being built much more tightly and better insulated so that the draft effect of removing air from the house in the form of combustion air has become a more readily recognized problem.
The prior art has long recognized (for example, see Patent 948,007) that fireplaces can be operated more efficiently if air is supplied to the fireplace from outside the house. It has also been recognized (see U.S. Pat. No. 3,180,332) that in addition to supplying air from outside the house, it may be advantageous to supply the combustion air from remote locations, such as unheated foundation crawl-spaces and basement areas which are usually at lower temperatures than the living areas of a house. One of the more recent patents relating to the use of outside air is U.S. Pat. No. 3,845,754 that additionally discloses the use of a tempered glass screen which, when closed, prevents any air from being withdrawn from the fireplace room while, at the same time, allows the fire to heat the room by radiation and permits aesthetic enjoyment of the fire.
Another advantage of a fireplace as shown in U.S. Pat. No. 3,845,754 lies in the fact that when the tempered glass screen is in the shut position, the fire may be left unattended and allowed to die down overnight, and, even though the flue is not closed, no warm air will be drawn out of the house through the chimney.
While the above and other known improved fireplaces are generally effective in improving the heating and combustion efficiency, they suffer from several disadvantages. For example, these fireplaces require special conduits, as through outside walls, which cannot be installed without considerable inconvenience except at the time the house and fireplace are built. Another disadvantage of the prior art fireplaces of the type with which this invention is concerned lies in the fact that they do not provide for effective distribution of incoming combustion air or control over the rate and efficiency of combustion.